Cyclohexene production



Sept. .25, 1945. H. H. VOGE IYCLOHEXENE PRODUCTION Filed may 2, 1944 Losud Bq his A++Qrn2\.j

Patented Sept. 25, `1945 '2,3Ss,ss'sl AUNITED STATES PATENT OFFICE y cronolonuonon' i Y,

Hervey H. Vage, Berkeley, Calif., assignmm.,

Shell Development Company,

San Francisco,

Calif., a corporation of Delaware Application. May 2, 1944, Serial No. 533,763

(Cl. 26o-666) 11 Claims.

This invention relates to a process for the production of cyclohexene and relates more particularly to the conversion of cyclohexane to cyclohexene.l

f the unsaturated cyclic aliphatic hydrocarbons, cyclohexene nds application as the startcompoundsv comprise, for example, a cyclohexyl halide, from which the desired cyclohexene is thereafter produced by such methods as high temperature treatments or by heating at lower temperatures with quinoline or alcoholic potash, byheating in the presence of` water vin the presence of alkaline agents etc. Such processes 'are not only often cumbersome, but are4 generally relatively costlyvbecause of the nature of the individual chemical processing steps involved. Al

process enabling the veillcient manufacture of cyclohexene from a readily available material such as, for example, cyclohexane, in the absence of relatively complicated and costly intermediate chemical processing steps is, therefore,.of the utmost importance; Production of eyclohexene on a-practlcal scale by subjecting `cyclohexane to heretofore disclosed dehydrogenation conditions is not feasible since the reaction cannot be controlled to result in economically attractive yields of the desired cyclic olen and proceeds to the of a product consisting predominantly ,40

It is an object of the present invention to proformation of benzene.

cyclopentane. 'Resulting methylcyclopentane is catalytically dehydrogenated to methylcyclopentenes, and the methylcyclopentenes thus obtained subjected to catalytic olen isomerizing conditions-electing their conversion to cyclohexene.

Suitable charging material from which cyclohexene is produced in accordance with the invention comprises cyclohexane or cyclohexane-containing hydrocarbon mixtures obtained from any 'suitable source. Thus, the cyclohexane, or a hydrocarbon fraction comprisingit, may be ob'- tained by treatments comprising such steps as fractionation, solvent extraction, extractive distillation, etc., of naturally occurring hydrocarbon mixtures such as crude oils and natural gasoline, or of the products obtained in the thermal or catalytic treatment of such hydrocarbon mixatractivo hydrogenation, etc.

tures or distillate fractions `thereof. Such catalytic and thermal treatments, comprise, for example, cracking, reforming, polymerization, de-

In order to set forth more fully the nature of the invention, it will'be described herein with y reference to the attached drawing. in which Fig' ure 1 represents a more or less diagrammatic elevational view of one form of apparatus suitable for carrying out the process of the invention, and Figure 2 representsa more or less diagrammatic elevational view of one form of apparatus sultable for carrying out a preferred modiicationA of the invention. Parts of apparatus of Figures 1 and 2, which are identical, are indicated with like v reference characters. 'Cyclohe'xane, or a hydrocarbon mixture com--v prising cyclohexane, is passed through line I and suitable heating means, for example, a furnace v or heat exchanger 2, into a reaction zone. The

vide an improvedprocess' for the more emcient v production of cyclohexene from cyclohexane or hydrocarbon mixtures comprising cyclohexene. Other objects and advantages of the invention will become apparent from the following description thereof.

In 'accordance with the process of the invention, cyclohexane, optionally in adm ixture with other hydrocarbons capable or not of undergoing conversion under conditions of execution of the process and/or in the presence of inert gaseous material, is contacted with an isomerization catalyst imder naphthene isomerizing conditions effecting the conversion of cyclohexane to methyl-.

reaction zone may comprise a reactor l, for ex,

' ample of the mixer type. Within reactor 3, the

hydrocarbon stream is contacted with an isomerization catalyst under 'naphthene isomerizing conditions. Suitable isomerization catalysts comprise those containing a metal-halide of the Friedel-Crafts type, such as those comprising a halide of aluminum. Particularly suitable-catalysts comprise aluminum chloride per se dis;- solved and/or suspendedv in the hydrocarbon charge; pre-formed iiuid organo-aluminum halide complexes; isomerization catalyst of the molten salt type comprising, for example amolten mixture oi an aluminum halide and one or more metal halides. A particularly advantageous cata- 'lyst of the molten salt type comprises a solution of aluminum chloride in molten antimony trichloride. The isomerization is carried out in treated with an acidic material.

pretreatments comprise, for example, subjection' to elevated temperature, optionally in the presence of gaseous materials such as hydrogen, nitrogen, steam, gaseous materials comprising them, or contact with an inorganic mineral acid such as hydrogen chloride, etc. A particularly preferred type of catalyst comprises the adsorptive aluminous materials containing substantial amounts of gamma alumina that has been pre- By judicious control of heat input into coil 30, temperatures in the range of from about 300 C. to about 650 C., and preferably from about 350 C. to about 500 C., are maintained within reactor 33. Atmospheric or superatmospheric pressures may be maintained within reactor 33. Pressures close to atmospheric have been found suitable. A liquid hourly space velocity of, for example, from about 0.5 to about 25 is employed. Although adsorptive aluminous materials are preferred as catalysts for the isomerization of methylcyclopentenes, the invention is not necessarily limited thereto and other catalysts capable of activating the olefin isomerization reaction may be employed.

' Such catalysts comprise, for example, catalysts of the type of naturally occurring siliceous materials such as clays, bentonites or the like, alumina-silica compounds or mixtures thereof; zeolites; oxides of Be, Si, Ti, Th, V, Zr, Mn; etc. Other suitable catalysts are those comprising phosphoric acid and silica; as well as any acid of low volatility preferably on a solid oxide support material.

Under the above specied condition, methylcyclopentenes are converted to cyclohexeriev as evidenced by the following example.

Example III Methylcyclopentenes were contacted with an HC1 treated alumina at a temperature of 500 C. and atmospheric pressure at a liquid hourly space velocity of 19.2. Under these conditions about 12% of the charge was converted to cyclohexene and the balance consisted essentially of unreacted methylcyclopentenes. This represents a conversion of methylcyclopentenes to cyclohexenes equal to 80% of the equilibrium value for the temperature employed..

Reaction products comprising cyclohexene and unconverted methylcyclopentenes are passed through line 34 into a fractionator 35. Hydrocarbons comprising methylcyclopentenes are recycled from fractionator 35 through valved lines 35 and 31 into line 29. Hydrocarbons comprising cyciohexene are separated as a. nal product from fractionator 35 through valved line 3&3.

It has been found that methylcyclopentane when present in the methylcyclopentenes charged to reactor 33 will pass therethrough without any substantial part of the methylcyclo-` pentane undergoing any change under the specied olefin isometrization conditions. In a modification of the invention as illustrated in Figure 2 of the drawing, efiluence from the dehydrogenation reactor I8, comprising both methylcyclopentane and methylcyclopentenes, is passed through line 20 and cooling means 2l, directly into isomerization reactor 33. In passing there- 3 through under the speciiled isomerizing conditions, the methylcyclopentenes are selectively converted to cyclohexene. Substantial saving in 'cost is thus obtained by utilizing the available heat content of the dehydrogenation reactor ef- :tiuent in the subsequentisomerization reactor33. Eilluence from isomerization reactor 33 comprising methylcyclopentane, methylcyclopentenes, and cyclehexene is passed to an extractive distillation column 42 wherein it is extractively distilledin the presence of a suitable solvent capable of eiTecting separation of saturated hydrocarbons from cyclic olefins. Hydrocarbons comprising methylcyclopentane are taken overhead from column 42 and recycled through line 43 into line I4,

Solvent comprising cyclic olefins is passed from' column 42 into column 43 kwherein separation of oleflns and solvent is eiected, the solvent being returned tothe upper part of column 42. Hydrocarbons comprising methylcyclopentenes and cyclohexene are passed overhead from column 43 through line 44 into a fractionator 45. Hydrocarbons comprising methylcyclopentenes are separated as overhead in fractionator 45 and recycled through valved lines 46 and 4l to line 20 leading to the methylcyclopentene isomerization zone. The availablehcat content of the efiluence from reactor I8 will generally suilice to raise the recycled methylcyclopentenes entering line 20 through line 4'! to the desired isomerizing temperature. Additional adjustment of temperature within isomerizing reactor 33 is made by control of indirect heat exchanger lil'.4V Hydrocarbons comprising cyclohexene are taken from frac-v scope of the invention.

conversion of methylcyclopentenes to cyclohexene.

2. The process for the manufacture of cyclohexene from cyclohexane which comprises contacting cyclohexane with a catalyst comprising a metal halideV of the Friedel-Crafts type under naphthene isomerizing conditions effecting the conversion of cyclohexane to methylcyclopentane, contacting the resulting methylcyclopentane with a dehydrogenating catalyst under dehydrogenating conditions eecting the couver. sion of methylcyclopentane to methylcyclopentenes, and contacting the resulting. methylcyclopentenes with a catalyst comprising a solid nd y sorptive aluminous material under olefin isomertion.

izing conditions eiecting the conversion of methylcyclopentenes to cyclohexene.

3. The process for the manufacture of cyclohexene from cyclohexane which comprises contacting cyclohexane with a catalyst comprisingv a vhalide of aluminum under naphthene isomerizing conditions eecting the conversion of cyclohexane to methylcyclopentane, contacting the resulting methylcyclopentane witha dehydrogenatingcatalystl under dehydrogenating conditions adsorptive alumina under olefin isomerizing conditions effecting the conversion oi' methylcyclopentenes to cyclohexene.

v 5; The process for the productionof cyclovhexene from hydrocarbons comprising cyclohexane which comprises contacting said hydrocarbons comprising cyclohexane with a catalyst comprising a metal halide of the Friedel-Crafts type undernaphthene isomerizing conditions effecting the conversion of cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from theisomerizate, contacting said hydrocarbons comprising methylcyciopentane with a dehydrogenating catalyst under dehydrogenating conditions eiecting the conversion of methylcyclopentane to methylcyclopentenes, separating hydrocarbons comprising methylcyclopentenes from the products of said dehydrogenation, contacting said hydrocarbons comprising methylcyclopenteneswith a solid olefin isomerizing catalyst under olefin. isomerizing conditions eitecting the conversion oi methyloyclopentenes to' cyclohexene,` and separating hydrocarbons comprising cyclohexene from the products of said olefin isomerization.

6. 'I'he process for the production of cyclohexene from hydrocarbons comprising cyclohexane which comprises contacting said hydrocarbons comprising cyclohexane with a catalyst comprising a halide of aluminum under naphthene isomerizing conditions effecting the conversion of cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the isomerizate, contacting said hydrocarbons comprising methylcyclopentane with a dehydrogenating catalyst under dehydrogenating lconditions effecting the conversion oi' methylcyclopentane to methylcyclopentenes, sep'- arating hydrocarbons comprising methylcyclopentenes from the products of said dehydrogenation, contacting said hydrocarbons comprising methylcyciopentenes with a catalyst comprising a solid adsorptive aluminous material under olefin isomerizing conditions. eiecting the conversion of methylcyclopentenes to cyclohexene, and separating hydrocarbons comprising cyclohexene from the products of said olenn isomerizamethylcyclopentenes ina pentane from 7. I'he process for the production of cyclohexene from hydrocarbons comprising cyclohexane which comprises contacting said hydrocarbons comprising cyclohexane with a catalyst comprising a halide of aluminum under naphthene isomerizing conditions effecting the conversion of cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the isomerizate, contacting said hydrocarbons comprising methylcyclopentane with a dehydrogenating catalyst under dehydrogenating conditions edecting the conversion of `methylcyclopentane to methylcyclopentenes, separating hydrocarbons comprising methylcyclopentenes from the products of said dehydrogenation, contacting said hydrocarbons comprising methylcyclopentenes with a catalyst comprising adsorptive alumina under olefin isomerizing conditions effecting the conversion of methylcyclo-4 pentenes to cyclohexene, and separatingmydrocarbons comprising cyclohexene.. from the products of said olefin isomerization. s

8. The process for the production of cyclohexene from hydrocarbons comprising 'cyclohexane which comprisescontacting said hydrocarbons -comprising cyclohexane with a catalyst comprising a metal halide of the Friedel-Crafts type under naphthene isomerizing conditions effecting the conversion of cyclohexane to meth-v ylcyclopentane in a rst conversion zone, separating hydrocarbons comprising methylcyclothe eiiluencev of said first conversion zone, contacting said hydrocarbons comprising methylcyclopentane with a dehydrogenating catalyst under dehydrogenating conditions effecting the conversion of methylcyclopentane to second conversion zone, passing the eiiluence oi' zone directly into a third conversion zone in intimate contact with a solid olefin isomerizing cata.

lyst under oleiln isomerizing conditions eii'ecting the conversion of methylcyclopentenes to cyclohexene, and separating hydrocarbons comprising cyclohexene from the eiiluence of said.

third conversion zone.'

9. The process for the production of cyclohexene from hydrocarbons comprising cyclohexane which comprises contacting said hydrocarbons comprising cyclohexane with a catalyst comprising a halide ofalumlnum under naphthene isomerizing conditions effecting the conversion o! cyclohexane to methylcyclopentane in a first conversion zone, separating hydrocarbons comprising methylcyclopentane from the eiiluence ofl said liirst conversion zone, contacting said hydrocarbons comprising methylcyclopentane with a de- ,hydrogenating catalyst under dehydrogenating conditions effecting clopentane to methylcyclopentenes in a second conversion zone, passing the eiiluence of said second conversion zone directly into a third conversion zone in intimate contact with a catalyst comprising a solid adsorptivey aluminous material under olen isomerizing conditionsv effecting the conversion of methylcyclopentenesy to cyclohexene, and separating hydrocarbons comprising cyclohexene from the eiiluence of said third con-` version zone.

10. The process for the production of cyclohexene from hydrocarbons comprising cyclohexane which comprises contacting said hydrocarbons comprising cyclohexane with a catalyst comprising a-halide ot aluminum under naphthene isomerizlng conditions .enacting the conversion of cyclohenane to methylcyclopentane in said second conversion the conversion of methylcy-` second conversion zone, passing ythe eiiluence of said second conversion zone directly into a third conversion zone in intimate contact with a catalyst comprising adsorptive alumina under olefin isomerizing conditions'eilecting the conversion of.

methylcyclopentenes to cyclohexene, and separating hydrocarbons comprising cyclohexene from the eiiiuence of said third conversion zone.

l1. The process for the lproductionof cyclohexene from hydrocarbons comprising cyclohexane whichcomprises contacting said hydrocarbons comprising cyclohexane -with a catalyst comprisene, separately recovering hydrocarbon fractions clopentane in a nrst conversion zone. separating hydrocarbons comprising methylcyciopentane from the eiliuence of said nrst conversion zone, contacting said hydrocarbons comprising methylcyclopentane with a dehydrogenating catalyst under dehydrogenating conditions eiecting the 'conversion of methylcyclopentane to methylcyclopentenes in a second conversion zone, passing the eiiluence oi' said second conversion zone directly into a third conversion zone in intimate 'contract with a solid olefin isomerizing catalyst under olefin isomerizing conditions eilecting the conversion of methylcyclopentenes to cyclohexpredominating in methylcyclopentane, methylcyclopentenes, and cyclohexene respectively, recycling said hydrocarbons comprising methylcyclopentane to said second conversion zone, and recycling said hydrocarbons comprising methyl ing a metal halide of the Friedel-Crafts type l0 cyclopentenes to said third conversion zone.

under naphthene isomerizing conditions efecting the conversion of cyclchexane to methyicy- HERVEY. H. VOGE. 

